ZyXEL U-1496S Plus User Guide - Page 9

ITU-TSS International Telecommunications Union - Technical Standardization Sector, is

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signal is sent; character timing is recovered from the data itself. A PC's COM1 and COM2 are asynchronous serial ports. Most PCs' and Unix systems' serial data communications are asynchronous. The serial data communication on an IBM mainframe or mini is synchronous. WHAT IS UART UART (Universal Asynchronous Receiver Transmitter) is the device used in a DTE or DCE for asynchronous data reception and transmission. The normal UART device used in PCs is of the NS16450 type. For high-speed serial data receiving (38400 bps and up), the PC may not serve the UART fast enough and data may get lost. In this case, a UART with data buffer is needed, such as the NS16550A type. MODEM STANDARDS AND SPEEDS The CCITT (Comite International Telegraphique et Telephonique, now called ITU-TSS (International Telecommunications Union - Technical Standardization Sector), is the international standard-making body for telecommunication. They draft "recommendations". The recommendations they made for modem applications have a "V" prefix and are called V-series recommendations. The commonly used CCITT standards for 2-wire dial-up line are: V.32bis 14400/12000/7200 bps V.32 9600/4800 bps V.22bis 2400 bps V.22 1200 bps V.21 300 bps V.23 1200/75 bps Note: bis is the French word for second. In the USA, Bell Systems used to create the de facto standard such as Bell 212A for 1200 bps modems and Bell 103 for 300 bps modems. Everyone is following the CCITT standard now for newer and higher speed modems. ZyXEL U-1496 series modems support all the above mentioned modem standards and are compatible with existing modems. TYPE OF TELEPHONE LINE The commonly used phone service is a 2-wire dial-up line. Only two wires connect the modem to the phone company's central office. The same two wires are used for DC current feeding, ringing, dialing, on/off-hook monitoring, and signal transmission in both directions. This is the type of phone service most people have in their home or office. Since the same two wires are used for both transmitting and receiving signals, an echo of the transmitting signal will also be received and it is the modem receiver's task to remove the echo before demodulation.

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signal is sent; character timing is recovered from the data
itself.
A PC's COM1 and COM2 are asynchronous serial ports. Most PCs' and
Unix systems' serial data communications are asynchronous. The
serial data communication on an IBM mainframe or mini is
synchronous.
WHAT IS UART
UART (Universal Asynchronous Receiver Transmitter) is the device
used in a DTE or DCE for asynchronous data reception and
transmission. The normal UART device used in PCs is of the
NS16450 type. For high-speed serial data receiving (38400 bps and
up), the PC may not serve the UART fast enough and data may get
lost. In this case, a UART with data buffer is needed, such as
the NS16550A type.
MODEM STANDARDS AND SPEEDS
The CCITT (Comite International Telegraphique et Telephonique, now called
ITU-TSS (International Telecommunications Union - Technical Standardization Sector), is the
international standard-making body for telecommunication. They draft "recommendations". The
recommendations they made for modem applications have a "V" prefix and are called V-series
recommendations. The commonly used CCITT standards for 2-wire dial-up line are:
V.32bis
14400/12000/7200 bps
V.32 9600/4800 bps
V.22bis
2400 bps
V.22 1200 bps
V.21 300 bps
V.23 1200/75 bps
Note: bis is the French word for second.
In the USA, Bell Systems used to create the de facto standard
such as Bell 212A for 1200 bps modems and Bell 103 for 300 bps
modems. Everyone is following the CCITT standard now for newer
and higher speed modems.
ZyXEL U-1496 series modems support all the above mentioned modem
standards and are compatible with existing modems.
TYPE OF TELEPHONE LINE
The commonly used phone service is a 2-wire dial-up line. Only
two wires connect the modem to the phone company's central
office. The same two wires are used for DC current feeding,
ringing, dialing, on/off-hook monitoring, and signal transmission
in both directions. This is the type of phone service most people
have in their home or office. Since the same two wires are used
for both transmitting and receiving signals, an echo of the
transmitting signal will also be received and it is the modem
receiver's task to remove the echo before demodulation.